Register control system for a moving web



Oct. 4, 1966 c. A. LEWIS, JR., ETAL 3,

REGISTER CONTROL SYSTEM FOR A MOVING WEB Filed March 51, 1964 2 Sheets-Sheet 1 CORRECTlON COMPUTER FIG! FiGZ) FIG.5

COMPUTER INVENTORS CLARENCE A. LEWIS JR.

JAMES F. O'BRIEN BY ATTORNEYS DRIVE Oct. 4, 1966 c. A. LEWIS, JR, ETAL 3,276,647

REGISTER CONTROL SYSTEM FOR A MOVING WEB Filed March 51, 1964 2 Sheets-Sheet 2 INVENTORS CLARENCE A. LEWIS JR.

JAMES F. O'BRIEN A TORNEYS United States Patent O 3,276,647 REGISTER CONTROL SYSTEM FOR A MOVING WEB Clarence A. Lewis, Jr., Kinnelon, and James F. OBrien, Sussex, N.J., assignors to Champlain Company, Inc.,

Roseland, N.J., a corporation of New York Filed Mar. 31, 1964, Ser. No. 356,234

15 Claims. (Cl. 226-31) This invention relates to register control systems for repeat operations on a moving web.

The primary object of the invention is to generally improve such register control systems, and to provide a relatively simple and inexpensive system using solidstate circuitry, for position register.

Such systems may be too sensitive and unstable and may hunt excessively if it be sought to correct a registration error for each repeat length on a printed web. In accordance with a further feature and object of the pres ent invention, the system includes a compact sampling circuit utilizing solid-state components, and preferably having a selector switch whereby operation of the correction motor may be permitted for each repeat length, or every second repeat length, or every fourth repeat length, and so on, up to say every sixteenth repeat length.

Further objects center about the handling of a preprinted roll. The web may be unwound from the roll by means of feed units having metering rolls of fixed diameter driven by a main shaft. The web then may go to a print cylinder, or a rotary knife, or a rotary die, the diameter of which depends on the particular repeat length to be handled. The latter cylinder is driven in onefor-one relation to the repeat length. This requires a driven of variable ratio as between the metering rolls and the cylinder, and for this purpose the drive may include a positive infinitely variable drive unit. A preprinted roll may have a repeat length which varies slightly from the beginning to the end of a particular roll, or which may vary from one roll to another. This will cause errors which repeat successively in one direction, instead of being random.

In accordance with a further object of the present invention, an error trend is recognized by simplified solid state circuitry, and a second correction motor is provided which responds to such a trend by slightly varying the drive ratio in proper direction to reverse the trend. The drive ratio is adjusted until there are about the same number of lagging and leading errors, or in other words, until the errors are random instead of trending heavily in one direction.

In accordance with a further feature and object of the invention, the circuitry may include a selector switch which varies the trend requirement, that is, the proportion of like error pulses, say, four out of six, needed to signify the existence of a trend sufficient for the second correction motor to take corrective action by changing the actual drive ratio. This is in contradistinction to the register position correction which is taken care of by the first correction motor.

To accomplish the foregoing general objects, and other more specific objects which will hereinafter appear, our invention resides in the register control elements and their relation one to another, as are hereinafter more particularly described in the following specification. The specification is accompanied by drawings in which:

FIG. 1 is a schematic diagram for apparatus embodying features of the invention;

FIG. 2 is explanatory of a phase micrometer used in FIG. 1;

FIG. 3 is a time diagram showing the relation of a scanner pulse to adjacent gate pulses;

3,276,647 Patented Oct. 4, 1966 FIG. 4 is an electrical block diagram showing the circuitry used in the system; and

FIG. 5 shows a modification of the apparatus shown in FIG. 1.

Referring to the drawing, and more particularly to FIG. 1, a preprinted web 32 is drawn from a web roll 34 by means of pull roll 36 cooperating with a pressure roller 38. Pull roll 36 is driven by a main shaft 40 which also drives a rotary cylinder 42, which may be a print cylinder or a rotary knife or a die. Inasmuch as feed roll 36 is kept constant in diameter, while cylinder 42 is changed according to the repeat length of the printed matter on the web, the drive ratio to cylinder 42 must be variable. In the present case, the drive is through a positive infinitely variable drive 44 having a wide output range, say two-toone. This drives a shaft 46 which drives cylinder shaft 48 through a running register 50 of the planetary or differential gear type. The position register of the cylinder 42 may be adjusted by means of a correction motor 52 controlled by circuitry in a correction computer 54.

The web 32 is scanned by a photoelectric eye or photodiode scanner 56 to produce target pulses which may be compared with pulses obtained from a phase micrometer 58 which is driven in one-to-one ratio with the rotary cylinder 42. Such phase indicating devices as 58 are known and need not be described in full detail.

Its general nature will be seen in FIG. 2, it comprising a disc or cup 60 rotated by shaft 62 and having a pair of displaced slots 64 and 66. These are illuminated by stationary lamps 68 and 70, the illumination from which is received by photodiodes 72 and 74. The slots 64 and 66 may be say 10 of arc in length for a long repeat length, say 18 to 36 inches, and they are angularly displaced to provide a dead zone therebetween.

The web scanner is also a known device, and needs no detailed description. It comprises a lamp, a photodiode, optics, and an amplifier, the latter preferably being transistorized.

When the machine is in register, that is, when the cylinder operates in proper position with respect to the printing on the web, a web pulse shown at 80 in FIG. 3, comes between leading and lagging pulses or gates shown at 82 and 84. If the web pulse 80 occurs during either the lead pulse or the lag pulse, an out-of-register condition exists, and the correction computer 54 (FIG. 1) energizes the correction motor 52 in proper direction to move the web pulse back into the dead zone, thereby reestablishing the desired register. With the present system the dead zone may be reduced to a very small value, if desired, down to say five thousandths of an inch and even less of web.

The P.I.V. drive 44 may have its drive ratio varied by means of a second correction motor Q0 which is also controlled by part of the circuitry at block 54. The circuitry includes means to sense a trend of corrections, and if the trend is definitely in one direction or the other, the ratio of the drive 44 maybe slightly varied in proper direction to reverse the trend.

The electrical circuitry may be described with reference to FIG. 4 of the drawing, referring to which the phase micrometer 58 produces the lead gate pulse and lag gate pulse shown at 82 and 84 in FIG. 3. The web scanner 56 produces the pulse in FIG. 3) which represents the position of the web target with respect to the phase micrometer. If the web pulse occurs between the lead and lag pulse, as shown in FIG. 3, register is assumed to be acceptable. If however, the web pulse occurs simultaneously with either the lead or lag pulse, a correction increment is introduced to the web by means of the reversible motor 52.

This is preferably a two phase motor of the Slo-Syn permanent magnet type. The two field windings for the two phases are indicated in FIG. 4 at 132 and 134. The correction increment is of short time duration, say one tenth of a second.

The web pulse from scanner 56 goes through a block 4 representing a light increase, light decrease switch which is set in proper position, that is, if the background is dark and the web target is light, the switch is set in the light increase position. Conversely, if the background is light, and the target is dark, the switch is set in the light decrease position.

The pulse is then amplified in amplifier 5 and then goes to a sensitivity switch in block 6. This is normally set in sensitive position, for response to a small contrast at the target on the web, but when first setting up the apparatus to handle a new printed web, the switch may be put in a desensitized position so that background variations will not affect the system.

The pulse is sharpened and conditioned in a Schmidt trigger circuit ST3, and then moves through AND gate 25, the output of which is supplied to AND gates 7 and 8.

The leading and lagging gate pulses from phase micrometer 58 are supplied to Schmidt trigger circuits ST1 and ST2 which provide gate pulses which are sharp and which are constant in amplitude. These are combined at the AND gates 7 and 8 with the conditioned web target pulse.

The circuitry centering beneath the five-pole switch S1 constitutes an electronic sampler circuit which is not described now but is described later. For the present purpose, the switch S1 is assumed to be in its leftmost position, in which case there is no sampling, that is, a target pulse from scanner 56 is received and used for every repeat length, as though there were no sampling circuit.

This is so because AND gate 25 then has through wire 150 a DC. level which acts as one input such that the AND gate 25 is receptive to all pulses received from scanner 56. The actual power supply detail is not shown because FIG. 4 is a conventional block diagram, and the details for the blocks shown may be conventional.

The output of ANDgate 25 appears at either AND gate 7 or 8, and combines with either the lead or lag gate pulse to actuate a one shot mono-stable multivibrator in block 9 or block 10, respectively. Thus, the web pulse appears with either the lead or lag gate pulse, and actuates the appropriate one-shot multi-vibrator whose output appears at either gate -11 or gate 12. These are also AND gates.

The other input to AND gates 11 and 12 is a double frequency pulse from an oscillator 13. Thus, if'either one shot circuit 9 or is actuated, double frequency pulses will appear at the output of either gate 11 or gate 12. In the present case, in which the A.C. supply to the motor 52 is a '60-cycle supply, the frequency from the frequency doubling source 13 is 120 cycles per second.

The reversing action provided for motor 52 may be explained with reference to the upper part of FIG. 4, by first assuming that the silicon-controlled rectifiers SCR1 and SCR2 are replaced by a single-pole switch, and similarly that SCR3 and SCR4 arereplaced by a singlepole switch. If the upper switch were closed, the field winding 132 would be energized through conductor 140 directly from the 110 v. source, and the other winding 134 would be energized through a phase shifting capacitor 136. The motor then would rotate in one direction. If instead the switch corresponding to SCR3 and SCR4 were closed, the field winding 134 would be energized through conductor 142 directly from the 110 v. source, and the other field winding 132 would be energized through phase shifting capacitor 136. The motor then would rotate in reverse direction.

In this system, the error is on or off, and the correction motor 52 turns on or off. If a pulse occurs in I to supply the trigger pulses.

the dead zone, there is no correction. If a pulse occurs in the lead gate or in the lag gate, there is an appropriate correction through the silicon-controlled rectifiers. Two are needed because the motor is energized by both positive and negative halfwaves. For brevity the pair may be called an SCR switch for A.C. The other two are needed to supply the motor for reverse operation.

In FIG. 4 the motor armature (not shown) is subjected to field windings 132 and 134. A common wire for the A.C. supply is shown at 138. The other supply wire is either 140 or 142, depending on the energization of one pulse transformer T1 or the other transformer T2 Because each switch comprises two oppositely faced silicon-controlled rectifiers, each transformer has two secondaries. The control electrodes of the silicon-controlled rectifiers are pulsed from the double frequency source 13, through either transformer T1 or T2. The duration of this series of pulses is set by the time delay of the one shot multi-vibrators 9 and 10. The direction of rotation depends on which transformer receives the c.p.s. pulses.

THE SAMPLING CIRCUIT To make the system more stable, it may be desired to sample the error intermittently instead of measuring it for each sheet. This is so because it takes time for a correction to manifest itself further down the line at the scanner. Thus, an error will be shown although perhaps already sufficiently corrected, and this leads to over-correction and hunting or instability when seeking a high degree of accuracy.

In the present system a circuit is provided which is controlled by a selector switch and which results in sampling once for every sheet, or once for every second sheet, for every fourth sheet, for every eighth sheet, or for one in sixteen sheets.

The electronic sampler provides stability despite the system lag, that is, despite the fact that a correction may be almost instantaneously introduced to the web, and yet the result of the correction not be apparent at the scanner until some time later when the equilibrium conditions are established. The sampling circuit affords time for the correction to be absorbed or recognized.

The sampler functions as follows. Flip-flop stages FFl, FF2, FF3, and FF4 are bi-stable elements connected to act as a binary counter which counts to sixteen. It is not desirable to directly sample the web scanner pulses because before the action of the gate there may be many excess or false pulses from the scanner caused by the overall printing on the web, and it is only after the gate action of the phase micrometer 58 that the true target pulse is selected from all the other pulses. For this reason, the sampling counter now described is applied to a gate pulse rather than a scanner pulse. The lead gate is used because it precedes the target pulse, and, subject to the sampler action, makes AND gate 25 receptive to the target pulse for the selected sampling interval.

The rotary switch S1 in this instance is a five-pole switch. Disregarding the lower pole 152, the four upper poles are related to the four flip-flop circuits shown directly therebelow. In the first or leftmost position of the switch all four flop-flop stages are inhibited and do'not function. This is so because the left side of each flip-flop stage is grounded as shown at 154, to prevent the flipflop from functioning. Gate 14 thus receives all four inputs on the four conductors shown leading into gate '14, and therefore delivers a continuous output to conductor 150, which in turn is an input to gate 25, as previously explained, making it receptive to all scanner pulses.

When the switch S1 is in the second position, flip-flops FF2, FF3, and PM. are grounded at 154 as previously described, and thereby made inoperative. However, flipflop FFI is made operative since its output is not grounded, the contacts at the left switch pole being open in all positions except the first. Thus, it will produce an output for every second lead gate pulse, and the AND gate 25 is made receptive through conductor 150 for only every second repeat length.

In the third position of switch S1, the flip-flops FPS and FF4 are grounded at 154, and the flip-flops FF1 and FFZ are effective, thus delivering an output for every fourth gate pulse, with the result of sampling for every fourth repeat length. In similar fashion, in the fourth position, only the last flip-flop circuit is grounded, and the circuit is active for only every eighth repeat length; and in the fifth position the circuit is active for every sixteenth repeat length, none of the flip-flop circuits then being grounded.

Usually .a part, say 66% of the total correction is seen 'by the scanner in the interval that it takes the web to travel the distance from one pair-of feed rolls to the next. It is desirable to set the sampler at the lowest feasible selector position, and to make the greatest feasible amount of correction in each correction cycle, in order to minimize waste of web material caused by large errors. However, these requirements are incompatible with stable operation, because large corrections in rapid succession produce instability. Without sampling intervals, the correction increments established by one-shot circuits 9 and 10 would have to be exceedingly short for stable operation, and the correction for each repeat length would be minute and relatively ineffective. By sampling and correcting at intewals, stability may be maintained while using longer correction intervals at the one-shot circuits 9 and 10, sulficient to attain a greater total correction. Moreover, the sampling procedure compensates for the lag caused by the length of web between successive pairs of feed rolls, which in some cases may be substantial, and this compensation also contributes to stability. The optimum setting is such that the lag introduced by the sampler is equivalent to the lag that is inherent to the operation of the system, and usually is proportional to the length of web between the successive pairs of feed rollers involved.

THE TREND CIRCUIT A problem arises when unreeling and cutting a previous ly printed web. This may have an error which varies from the outside of the roll toward the inside of the roll. For example, the outside may become damp and the repeat length is different from inside where it is dry. The present system includes a circuit which recognizes a trend. If say four out of five measurements call for advance, then a correcting motor is used to neutralize the trend, and finally a condition is reached where the error floats back and forth around zero.

The trend computer usually is utilized only when preprinted web is being converted, but it can be used at any time, for example to correct undesired drift in a PIN. drive. A method of compensating for repeat length variation in a preprinted roll is most advantageous because repeat lengths vary considerably from roll to roll of stock, or from the beginning to the end of a particular roll of stock. The present circuit, shown in the lower right of the diagram, monitors in groups the number of advance or retard corrections derived from the computer, and appropriate corrections of the P.I.V. drive ratio are made through a second correction motor 90 in such a manner as to reestablish a more nearly equal or random distribution of advance and retard corrections.

The motor 90 again is preferably a Slo-Syn two-phase motor supplied from a single-phase source, and controlled by silicon-controlled rectifier switches and a double frequency pulse supplied through pulse transformers T3 and T4. The double frequency is supplied from source 160. The circuit may include a two-pole switch S2 which varies the trend requirement, that is, the number of like error pulses in groups of pulses, needed to signify the existence of a trend sufficient to take corrective action.

The present trend circuit has the advantage of being non-recursive, that is, it responds to error pulses in predetermined groups, and recycles at the end of each group in order to begin response anew to error pulses in the next group, thus discarding What may have been random errors in all preceding groups. For example, if the recycle group is selected to be six repeat lengths, a trend is established at four out of siX repeat lengths.

For flexibility in operation the specified requirement may be varied, and in the present circuit this is done by varying the size of the group. Specifically, the present circuit provides for a correction response to four out of four, four out of five, four out of six, or four out of seven repeat lengths. For determining the group this uses a binary counter with three stages, but by adding another stage the group may be lengthened to sixteen, and so forth. Other counters total the number of advance and retard pulses, and in the present case the said counters have two stages for a count to four, but obviously could have additional stages.

Referring now to the lower right-hand portion of FIG. 4, the flip-flop circuits FFS, FF6, and FF7 are bi-stable elements connected to operate as a counter for the group, to a total of eight, and through switch S2, indicated connections can be made to AND gate 16 and through another gate 17, such that the counter is reset or recycled every five, six, seven or eight repeat lengths or signals derived from the electronic sampler. Thus, these three stages consist of a recycling counter, the recycling number of repeat lengths being determined by the setting of switch S2 When as here illustrated, a sampling circuit is employed, the mention above of repeat length really refers to the utilized samples. If the sampler is set to utilize only each fourth repeat length, a group of five referred to above would be five samples, or twenty repeat lengths; a group of six would be six samples or twenty-four repeat lengths; and so on.

The effective repeat length or sample (depending on the position of selector switch S1) manifests itself through conductor 162 which extends from the sampler to the group counter. Assume switch S2 is in the leftmost or first position, which corresponds to a group of five, as marked. Starting from zero, the counter will count until its contents equal five, at which time the output of flipflop FF7 combines with the output of flip-flop FFS at the input to AND gate 16. The output of gate 16 through gate 17 recycles the counter to zero through conductor 164. This operation is repeated for every five samples.

The counter for the advance signals comprises the bi-stable elements or flip-flops FF8 and FF9, and the counter for the retar signals comprises the bi-stable elements or flip-flops FF10 and FF11. These are reset when the main group counter is recycled through its conductor 164. Their reset also is from the gates 16 and 17, but is through conductor 166.

If before recycling there are four advance signals (or sampled advance signals), an output pulse is provided from flip-flop FF9, through AND gate 19, and activates a one-shot circuit 21, which establishes the length of each corrective operation of the motor 90, say a tenth of a second. The output of one-shot circuit 21 combines With the double frequency circuit 160 at AND gate 23, thereby app-lying the double frequency to pulse transformer T3, and in effect closing the AC. switch comprising the siliconcontrolled rectifiers SCRS and SCR6, as previously explained for position correction motor 52.

It will be seen from inspection of the diagram that motor again is a two-phase motor operated from a single-phase supply, with either winding energized directly, and the other energized through a phase shifting capacitor, as was described for motor 52. Also, that the reversing control of motor 90 is through two pairs of oppositely polarized silicon-controlled rectifiers, the control electrodes of which are coupled through pulse transformers T3 and T4, each having two secondaries, all as was described for motor 52.

It will be recalled from FIG. 1 that motor 90 varies the drive ratio of the P.I.V. drive. Motor 90 rotates in proper direction to reduce the error trend.

Without repeating in detail, it will be understood that four retard pulses in a row cause the double frequency source 160 to be coupled through AND gate 24 and transformer T4 to the control electrodes of silicon-controlled rectifiers SCR7 and SCR8, thereby driving motor 90 in opposite direction to reduce the error trend.

With the selector switch S2 set in the position marked 5, the group counter will recycle every fifth repeat length or sample. Four consecutive advance or retard error signals are needed to produce an output. Since an advance or retard error signal pulse follows (in time) the gate signal which goes to the group counter, it is possible to have a count of one in the error counter when the group counter reads zero. It follows or is later in time because the group count is taken from the leading edge of the lead gate, and therefore is necessarily ahead of the web scanner pulse.

Because the error counters have only two binary stages, they automatically recycle to zero on a count of four. If the next signal is an error in the same direction, the counter has a count of one and is then reset when the group is recycled. If the error count on the counter FF8, FF9, (or on counter FF10, FFll) is only one, it is reset through conductor 166, as previously described.

There remains the problem of resetting these error counters when they have a count of more than one and less than four at the end of the group. A delay circuit 18 is provided in a conductor 168 leading from AND gate 16 to inhibited AND gates 19 and 20. This would not affect the operation previously described, but now becomes significant. With flip-flops FPS and FF9 containing a count of two or three, flip-flop FF9 would emit a pulse when it is reset by the counter through conductor 166. This pulse would produce an erroneous signal, which in turn would operate the correction motor. To prevent this, the reset pulse from the group counter (between gates 16 :and 17) is delayed so that AND gates 19 and 20 are inhibited by their connection to the group counter through conductor 168 before the error counter is reset through conductor 166. The time delay of this circuit is in the order of magnitude of one microsecond, and therefore does not aifect the normal operation previously described.

The gates 19 and 20 are inhibited AND gates, and pass an output from either error counter in the absence of a signal on conductor 168. With a signal on conductor 168, the gates are inhibited and block the output.

Previous to the recycling or reset pulse from the group counter, an inhibit pulse occurs at gates .19 and 20. At the instant that the reset pulse appears on line 166 due to rrecyling, an output of gate 16 appears at the delay circuit 18. Because of the delay, this pulse prevents the gates 19 and 20 from passing a pulse from flip-flops FF9 or FFll when they are reset. Gates 19 and 20 are normally inhibited; they conduct when there is a signal on line 168; but in the present case that signal is delayed and therefore gates 19 and 20 do not conduct.

As so far described, the group has been assumed to be five. If the switch S2 is moved to the second position, the group length is six. The operation then is substantially the same as previously described, except that the recycling of the group counter does not take place until a count of six, and the corresponding reset signal through conductor 166 to reset the error counters is also applied at a group count of six. There must now be four error pulses out of five, instead of four out of four, the last or sixth pulse in the group acting to recycle the group.

Similarly, when switch S2 is put on the third contact, the group length is seven, that is, the group is recycled on a count of seven, and a correction is initiated if the error count is four in six. Again with the switch on the last contact, the group length is eight, and the group counter recycles on a count of eight, while correction at motor is initiated if the error count reaches four out of seven.

Because the error pulses must reach a total of four before another pulse recycles the group counter, in practical effect this system calls for four like error pulses out of four samples (when the group is five), four out of five (when the group is six), four out of six (when the group is seven), and four out of seven (when the group is eight).

The purpose of the fifth pole 1 52 of the sample selection switch S1 is as follows: when set in position -1, the group counter counts the lead gate pulses directly from Schmidt trigger 1, by way of conductor 17 0 and conductor 162. In all other positions of switch S1, the group counter counts the sampled gate signals. These derive from the AND gate 14 to switch pole 152 and thence through conductor 162 to the trend circuit.

ALTERNATE MECHANISM Modifications of the mechanism shown in FIG. 1 may be made, and one such modification is shown in FIG. 5. In this case, as in FIG. 1, the web 232 is drawn from a roll 234 by means of feed rolls 236 and 238. A main difference is that position registration is obtained by means of a movable compensator roller 250, instead of by means of a running register. The position of compensator roller 250 is adjusted by means of a correction motor 252 driving a screw 253.

The second operation on the web is performed by means of a rotary knife or other cylinder 2-42 driven by a shaft 248, and again there a phase micrometer 258 which turns in one-to-one ratio with cylinder 242. The web is scanned by a scanner 256, and a computer 254 controls both the position correction motor 252, and the ratio correction motor 290.

As before, the speed of shaft 240 in relation to the speed of shaft 246 must be varied because the feed roll 236 is constant in diameter, whereas the operating roll or die 242 turns in one-to-one ratio with the repeat length of the printing on the web. This difference is obtained through a positive infinitely variable drive 44, and it is the drive ratio of this that is varied by correction motor 290.

Another difference illustrated in FIG. 5 is that the main drive is here applied to shaft 246 instead of shaft 240, that is, to the operating cylinder 242 instead of the metering roll 236.

It should be understood that While we have shown a rotary device at 42 in FIG. 1, the present system is also applicable to .a punch press of the known reciprocating type for scoring, cutting, creasing, or the like. Such a punch press operates on an intermittently moved web, but the web is first drawn at uniform velocity by feed rolls such as the rolls 36, 3'8 acting as metering rolls. Moreover, the web may be coming from a printing press instead of a roll. The significant thing here is that the punch press reciprocates once for each repeat length, and therefore substantial changes in drive ratio may be needed, and are provided by means of the drive 44 in FIG. 1 between the shaft 40 which drives the metering feed roll, and shaft 46 which in such case drives the punch press instead of the rotary device 42. The scanner 56 again is located close to the punch press, and the phase micrometer 58 is mounted on a one-to-one drive shaft of the punch press. As is well known, intermittently rotatable feed rolls at the punch press accelerate and decelerate the web, and a slack loop is provided between the continuous feed roll 36 shown in FIG..1, and the intermittently driven feed rolls (not shown) located at and forming a part of the punch press.

In FIG. 1, it should be understood that the roll 42 (or roll 242 in FIG. 5) having a peripheral length equal to the repeat length of the print on the web may be an embossing roll, or a print roll adding printed matter to a preprinted web. In the case of a simple rotary shear knife the diameter would not matter, since it does not run in tight web engagement, and there would be no need to change the cylinder diameter for a change in repeat length, but the invention applies exactly as described above because the knife must be turned in one-to-one ratio with the repeat length.

The repeat length to be handled may be varied over a wide ratio if the drive 44 is correspondingly variable over a wide ratio. Moreover, if desired or necessary a changegear box may be provided in addition to the infinitely variable drive 44. The variable drive may be a PIV drive made by Link Belt Co. or a Reeves drive, or a Graham drive, but the latter is variable over only a small range and therefore usually would 'be combined with a change gear box in order to provide a wide range of variation.

In the present system, the circuitry and components are usable for small or large correction motors because of the great range of a silicon-controlled rectifier. The same rectifiers can be used for motors ranging from to nearly a horsepower, assuming SCR units which handle 6 amperes at 110 volts, which is a commercially available and inexpensive commercial size.

It is believed that the construction and operation of our improved registration control system, as well as the advantages thereof, will be apparent from the foregoing detailed description. It will also be apparent that while we have shown and described the invention in a preferred form, changes may be made without departing from the scope of :the invention, as sought to be defined in the following claims.

We claim:

1. A register control system for a moving web, comprising a web scanner to detect an error in registration, a two-phase correction motor, a capacitor connected to the two field windings of the motor for shifting the phase of one field winding relative to the other, a single-phase A.C. supply for said motor, a pair of opposed silicon-controlled rectifiers connecting the A.C. supply to one field winding of the motor, a second pair of opposed silicon-controlled rectifiers connecting the A.C. supply to the other field winding, .a double frequency supply source to pulse one or the other pair of silicon-controlled rectifiers to make them conductive, circuitry controlled by the web scanner to feed the double frequency supply to the control electrodes of that pair of silicon-controlled rectifiers which drives the correction motor in that direction which tends to reduce the error in registration, and means to limit each operation of the correction motor to a desired brief interval, in the order of a fraction of a second.

2. A register control system for a moving web, comprising a web scanner to detect an error in registration, a twophase Slo-Syn type correction motor, a capacitor connected to the two field windings of the motor for shifting the phase of one field winding relative to the other, a single-phase A.C. supply for said motor, a pair of opposed silicon-controlled rectifiers connecting the A.C. supply to one field winding of the motor, a second pair of opposed silicon-controlled rectifiers connecting the A.C. supply to the other field winding, a double frequency supply source to synchronously pulse one pair or the other pair of silicon-controlled rectifiers to make them conductive, circuitry controlled by the web scanner to feed the double frequency supply to the control electrodes of that pair of silicon-controlled rectifiers which drives the correction motor in that direction which tends to reduce the error in registration, and a monostable multivibrator unit disposed in said circuitry to limit each operation of the correction motor to a desired brief interval, in the order of a fraction of a second.

3. A register control system for a moving web, comprising a web scanner to detect an error in registration, a reversible correction motor, means responsive to scanner pulses to operate the correction motor in that direction which reduces an error, and sampling circuitry including a series of bistable elements connected to make up a counter system and receiving pulses one for one with the aforesaid scanner pulses, means responsive to an output derived from the counter system for preventing operation of the correction motor, and a selector means to select desired derived counter system outputs, whereby the correction circuitry is made active at correction intervals greater than the repeat interval, the said correction intervals being deemed by the said selector means.

4. A register control system for a moving web, comprising a web scanner to detect an error in registration, means to provide a gate pulse to select a web target pulse for each repeat length, a reversible correction motor, means responsive to said pulses to operate the correction motor in that direction which reduces an error, and sampling circuitry including a series of bi-stable elements connected to make up a binary counter and receiving said gate pulses, and means responsive to an output derived from the counter for preventing operation of the correction motor, whereby the correction circuitry is made active at intervals greater than the repeat interval.

5. A register control system for a moving web, comprising a'web scanner to detect an error in registration, means to provide a gate pulse to select a web target pulse for each repeat length, a reversible correction motor, means responsive to said pulses to operate .the correction motor in that direction which reduces an error, and sampling circuitry including a series of bi-stable elements connected to make up a binary counter and receiving said gate pulses, means responsive to an output derived from the counter for preventing operation of the correction motor, and a selector switch to select desired derived counter outputs, whereby the correction circuitry is made by said selector switch to be active for every repeat length, or every second repeat lenth, or every fourth repeat length, and so on, depending on the position of the selector switch.

6. A register control system for a moving web, comprising a web scanner to detect an error in registration, a reversible correction motor, means responsive to scanner pulses to-operate :the correction motor in that direction which reduces an error, and sampling circuitry including a series of bi-stable elements. connected to make up a counter system and receiving pulses one for one with the aforesaid scanner target pulses, means which is made receptive to the scanner pulses by an output derived from the counter system, and selector means to select desired derived counter system outputs, whereby the correction circuitry is made active at intervals greater than the repeat interval.

7. A register control system for a moving web, comprising a web scanner to detect an error in registration, means to provide a gate pulse to select a web target pulse for each repeat length, a reversible correction motor, means responsive to said pulses to operate the correction motor in that direction which reduces an error, and sampling circuitry including a series of bi-stable elements connected to make up a counter system and receiving pulses one for one with the aforesaid scanner target pulses, and means which is made receptive to the scanner pulses by an output derived from the counter system whereby the correction circuitry is made active at intervals which are a multiple of the repeat interval.

8. A register control system for a moving web, comprising a web scanner to detect an error in registration, means to provide a gate pulse to select a web target pulse for each repeat length, a reversible correction motor, means responsive to said pulses to operate the correction motor in that direction which reduces an error, and sampling circuitry including a series of bi-stable elements connected to make up a counter system and receiving pulses one for one with the aforesaid scanner target pulses, means which is made receptive to the scanner pulses by an output derived from the counter system, and selector means to select desired derived counter systern outputs, whereby the correction circuitry is made active at intervals which are a multiple of the repeat interval.

9. A register control system for a moving web, comprising a web scanner to detect an error in registration, means to provide a gate pulse to select a web target pulse for each repeat length, a reversible correction motor, means responsive to said pulses to operate the correction motor in that direction which resduces an error, and sampling circuitry including a series of tbi-stable elements connected to make up a counter system and receiving said gate pulses, and an AND gate which is made receptive to the scanner pulses by an output derived from the counter system, whereby the correction circuitry is made active at intervals which are a mutilple of the repeat interval.

10. A register control system for a moving web, comprising a web scanner to detect an error in registration, means to provide a gate pulse to select a web target pulse for each repeat length, a reversible correction motor, means responsive to said pulses to operate the correction motor in that direction which reduces an error, and sampling circuitry including a series of .bi-st-able elements connected to make up a binary counter and receiving said gatepulses, an AND gate which is made receptive to the scanner pulses by an output derived from the counter, and a selector switch to select desired counter outputs, whereby the correction circuitry is made by said selector switch to be active every repeat length, or every second repeat length, or every fourth repeat length, and so on, depending on the position of the selector switch.

11. A register control system for a moving web acted on by two spaced mechansim-s one of which has a feed roller of constant diameter regardless of repeat length on the web, and the other of which is driven in one-to-one relation with the repeat length, said system comprising rotating drive means connecting said mechanisms and including a positive infinitely variable drive device having a reversible correction motor for changing its drive ratio, a web scanner to detect an error in registration, and a trend-counteracting circuitry for controlling said reversible correction motor, said circuitry including a group counter for receiving repeat length pulses, an advance error counter for receiving advance error pulses, a retard error counter for receiving retard error pulses, said group counter having a group count higher than that of the error counters, means responsive to a desired total on the advance error counter for driving the correction motor to change the drive ratio in that direction which reduces the error, means responsive to the retard error counter to drive the correction motor in opposite direction, means to recycle the group counter on reaching a desired group count, and means to reset the error counters when the group counter is recycled.

12. A register control system for a moving web acted on by two spaced mechanisms one of which has a feed roller of constant diameter regardless of repeat length on the web, and the other of which is driven in one-to-one relation with the repeat length, said system comprising rotating drive means connecting said mechanisms and including a positive infinitely variable drive device having a reversible correction motor for changing its drive ratio, a position register means between said mechanisms, a reversible correction motor for said position register means, a web scanner to detect an error in registration, means to provide a gate pulse to select a web target pulse for each repeat length, and trend-counteracting circuitry for controlling said reversible ratio correction motor, said circuitry including a group counter for receiving gate pulses, an advance error counter for receiving advance error pulses, a retard error counter for receiving retard error pulses, said group counter having a group count higher than that of the error counters, means responsive to a desired total on the advance error counter for driving the ratio correction motor to change the drive ratio in that direction which reduces the error, means responsive to the retard error counter to drive the ratio correction motor in opposite direction, means to recycle the group counter on reaching a desired group count, means to reset the error counters when the group counter is recycled, and additional circuitry responsive to the web scanner for driving the position correction motor in one direction or the other for correction of position register.

13. A register control system for a moving web acted on by two spaced mechanisms one of which has a feed roller of constant diameter regardless of repeat length on the web, and the other of which is driven in one-toone relation with the repeat length, said system comprising rotating drive means connecting said mechanisms and including a positive infinitely variable drive device having a reversible correction motor for changing its drive ratio, a web scanner to detect an error in registration, and trend-counteracting circuitry for controlling said reversible ratio correction motor, said circuitry including a group counter made up of bi-stable elements for receiving repeat length pulses, an advance error counter made up of bi-stable elements for receiving advance error pulses, a retard'error counter made up of bi-stable elements for receiving retard error pulses, said group counter having at least one bi-stable element more than said error counters -to provide a group count higher than that of the error counters, means responsive to a desired total on the advance error counter for driving the correction motor to change the drive ratio in that direction which reduces the error, means responsive to the retard error counter to drive the correction motor in opposite direction, means to recycle the group counter on reaching a desired group count, and means to reset the error counters when the group counter is recycled.

14. A register control system for a moving web acted on by two spaced mechanisms one of which has a feed roller of constant diameter regardless of repeat length on the web, and the other of which is driven in one-toone relation with the repeat length, said system comprising rotating drive means connecting said mechanisms and including a positive infinitely variable drive device having a reversible correction motor for changing its drive ratio, a web scanner to detect an error in registration, means to provide a gate pulse to select a web target pulse for each repeat length, and trend-counteracting circuitry for controlling said reversible ratio correction motor, said circuitry including a group counter made up of bi-sta ble elements for receiving gate pulses, an advance error counter made up of bi-stable elements for receiving advance error pulses, a retard error counter made up of bi-stable elements for receiving retard error pulses, said group counter having at least one bi-stable element more than said error counters to provide a group count higher than that of the error counters, means responsive to a desired total on the advance error counter for driving the correction motor to change the drive ratio in that direction which reduces the error, means responsive to the retard error counter to drive the correction motor in opposite direction, means 'to recycle the group counter on reaching a desired group count, means to reset the error counters when the group counter is recycled, and a selector switch so connected to the bistable elements of the group counter as to permit selection of a desired group count.

15. A register control system for a moving web acted on by two spaced mechanisms one of which has a feed roller of constant diameter regardless of repeat length on the web, and the other of which is driven in one-toone relation with the repeat length, said system comprising' rotating drive means connecting said mechanisms and including a positive infinitely variable drive device having a reversible correction motor for changing its drive ratio, a position register means between said mechanisms, a reversible correction motor for said position retard error pulses, said group counter having at least one bi-stable element more than said error counters to provide a group count higher than that of the error counters, means responsive to a desired total on the advance error counter for driving the ratio correction motor to change the drive ratio in that direction which reduces the error, means responsive to the retard error counter to drive the ratio correction motor in opposite direction, means to recycle the group counter on reaching a desired group count, means to reset the error counters when the group counter is recycled, a selector switch so connected to the bi-stable elements of the group counter as to permit selection of a desired group count, and additional circuitry responsive to the web scanner for driving the position correction motor in one direction or the other [for correction of position register.

References Cited by the Examiner UNITED STATES PATENTS 2,052,255 8/ 1936 Shoults 226-30 2,230,715 2/ 1941 Cockrell 226-61 3,181,046 4/1965 Sutton 318345 ROBERT B. REEVES, Primary Examiner.

HADD S. LANE, Examiner. 

1. A REGISTER CONTROL SYSTEM FOR A MOVING WEB, COMPRISING A WEB SCANNER TO DETECT AN ERROR IN REGISTRATION, A TWO-PHASE CORRECTION MOTOR, A CAPACITOR CONNECTED TO THE TWO FIELD WINDINGS OF THE MOTOR FOR SHIFTING THE PHASE OF ONE FIELD WINDING RELATIVE TO THE OTHER, A SINGLE-PHASE A.C. SUPPLY FOR SAID MOTOR, A PAIR OF OPPOSED SILICON-CONTROLLED RECTIFIERS CONNECTING THE A.C. SUPPLY TO ONE FIELD WINDING OF THE MOTOR, A SECOND PAIR OF OPPOSED SILICON-CONTROLLED RECTIFIERS CONNECTING THE A.C. SUPPLY TO THE OTHER FIELD WINDING, A DOUBLE FREQUENCY SUPPLY SOURCE TO PULSE ONE OR THE OTHER PAIR OF SILICON-CONTROLLED RECTIFIERS TO MAKE THEM CONDUCTIVE, CIRCUITRY CONTROLLED BY THE WEB SCANNER TO FEED THE DOUBLE FREQUENCY SUPPLY TO THE CONTROL ELECTRODES OF THAT PAIR OF SILICON-CONTROLLED RECTIFIERS WHICH DRIVES THE CORRECTION MOTOR IN THAT DIRECTION WHICH TENDS TO REDUCE THE ERROR IN REGISTRATION, AND MEANS TO LIMIT EACH OPERATION OF THE CORRECTION MOTOR TO A DESIRED BRIEF INTERVAL, IN THE ORDER OF A FRACTION OF A SECOND. 